| Coal slime is the main by-product in the process of wet coal preparation,which contains a large amount of fine kaolinite.The presence of impurity elements such as carbon and iron is an important factor affecting the surface/interface properties of kaolinite and the adsorption properties of reagents.The lack of reagents that can separate fine kaolinite from coal slime water is the technical bottleneck of efficient treatment and resource utilization of coal slime water.In this study,the occurrence regularity of carbon and iron impurities in Coal measure kaolinite(CMK),and the mechanism of influence on CMK surface/interface active site and reagent adsorption were studied by means of test analysis,theoretical calculation and experimental verification.Flocculation and flotation test verification were also carried out.This study provides theoretical basis and technical support for the efficient settlement of slime water and the design and development of separation agents.Physical and chemical properties shows that Kaolinite is a Kaolinite group mineral with kaolinite-1MD as the main crystal form,and the crystal order is poor.Impurity atoms in CMK are mainly C and Fe.Isoelectric points(IEP)of CMK particles with median particle size D50 of 34.8?m,8.0?m,4.7?m and 0.3?m are 2.08,2.21,2.29 and 2.71,respectively.When the pH of the solution is greater than IEP,the Zeta potential is negative and the potential is positively correlated with pH.When the pH is greater than 7,it basically stabilizes between-50mV and-60mV.The study on the occurrence of impurity elements such as C and Fe shows that the main components of carbon impurities in coal measures kaolinite are C and O,the main carbon functional groups are aromatic carbon(C-C)and aliphatic carbon(C-H).The main oxygen functional groups are hydroxyl(-OH)and C-O bond.The main Fe elements in kaolinite are Fe2+replacing Al3+(denoted as "Na-Fe(?)_K")and Fe3+replacing Al3+(denoted as "Fe(?)_K")and Fe3+substituted Si4+(denoted as"Na-Fe(?)_K")in silicon-oxygen tetrahedron,and the main form was Fe2+?A13+.Oxygen-containing functional groups of different oxygen-containing units in coal can form hydrogen bonds with the surface of Fe(?)_K,and the Ph-OH group carbon is easier to adsorption on NA-Fe(?)_K(001)surface.Density functional theory study of pharmaceutical adsorption shows that the dodecyl amine DDA and oleic acid OA molecules/ions are mainly adsorbed on the surface of the ideal kaolinite particle(001)through hydrogen bond and electrostatic attraction,and the adsorption capacity of DDA is stronger than that of OA.DDA molecules,OA molecules and ions cannot spontaneously adsorb on the surface of ideal kaolinite(001).The Fe can promote the adsorption of DDA and OA on kaolinite,and DDA is more easily absorbable on all surfaces of Na-Fe(?)_K kaolinite than OA.The Fe can strengthen DDA+assorted on(001)surface,but unfavorable to the adsorption of DDA+on(001)surface.The presence of Fe greatly enhanced the adsorption of OAon the surface of kaolinite particles.Sedimentation and flotation test results show that OA is more easily adsorbed on the surface of CMK particles than DDA.The flotation recovery of coal-measure kaolinite by DDA increases slowly at first and then decreases with the increase of solution pH,and the optimal flotation pH is 4.0.Ion RNH3+and ion association(RNH3+)22+are the main effective components of DDA flotation.Flotation recovery of CMK by OA increased rapidly at first,then reached equilibrium and then rapidly decreased with the increase of solution pH.The optimal flotation pH was between 6.0 and 8.0,and the ion-molecular association H(RCOO)2-are the main effective components of OA for the flotation of CMK particles.When the pH 6.0-8.0,OA can effectively separate kaolinite from quartz and montmorillonite,while DDA cannot effectively separate kaolinite.Figure [73] Table [35] Reference [102]... |
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